It's still a female name (4)
I believe the answer is:
even
'it's still' is the definition.
('even' can be a synonym of 'still')
'a female name' is the wordplay.
'a female' becomes 'eve' (Eve is an example**).
'name' becomes 'n' (common abbreviation e.g. on forms).
'eve'+'n'='EVEN'
(Other definitions for even that I've seen before include "night" , "Late in the day" , "Flush" , "Constant" , "(Of a number) divisible by 2" .)